Previously, many types of swim fins have been used to provide an effective means to assist a person in propelling themselves through the water. A single fin has been the generally accepted method with some type of foot retaining device including, straps, shoes enclosing pockets, contoured openings, etc. Little attention has been given to the flexible action of the fin other than its direct resistance to the water or how they considered the ability of the swimmer's foot to flex within the foot retainer.
A search of the prior art did not disclose any patents that read directly on the claims of the instant invention, however, the following U.S. patents were considered related:
______________________________________ U.S. Pat. No. Inventor Issue Date ______________________________________ 1,607,857 Zukal Nov. 23, 1926 2,073,570 Sutherland Mar. 09, 1937 2,737,668 Cressi et al Mar. 13, 1956 3,019,458 De Barbieri et al Feb. 06, 1962 3,112,503 Girden Dec. 03, 1963 3,239,857 Gwynne Mar. 15, 1966 3,422,470 Mares Jan. 02, 1969 4,007,506 Rasmussen Feb. 15, 1977 4,541,810 Wenzel Sep. 17, 1985 4,738,645 Garofalo Apr. 19, 1988 4,752,259 Tackett et al Jun. 21, 1988 4,857,024 Evans Aug. 15, 1989 ______________________________________
Zukal, in U.S. Pat. No. 1,607,857, discloses a swimming device intended to be attached to the foot of the swimmer. Although not referred very clearly in the text, part of the device appears to be a shoe-like portion, shown in FIGS. 1, 3 and 4. Apart from disclosing a shoe-like portion, however, this reference is nothing like the disclosed invention.
U.S. Pat. No. 2,073,570 issued to Sutherland discloses a "swimming shoe" provided with wing members 17 attached to the shoe top 15. This prior art does disclose the feature of the ability of the swimmer to flex his foot inside the device, inasmuch as the shoe part of the device appears to be of fairly conventional design, and street shoes normally allow flexing of the feet of the wearer.
Cressi et al, in U.S. Pat. No. 2,737,668, directs their attention to a fin for a swimmer. The fin comprises a housing 3 for the foot having an opening 4 through which the toes of the swimmer project, and upturned side portions 5 having rounded edges 6, 7. As shown in FIG. 2, the housing 4 has a heel section for enclosing the foot of the swimmer and a slight bulbous region. However, the height of housing 4 is not sufficient to allow the swimmer's foot to flex within the shoe portion.
De Barbieri et al disclose in FIGS. 1, 2 and 4 of U.S. Pat. No. 3,019,458 a swim-fin having a shoe portion 1 from which integral heel and toe sections a and b extend upwardly. The shoe portion appears to be open at the toes.
U.S. Pat. No. 3,112,503 issued to Girden, as illustrated in FIGS. 2, 3 and 6, discloses a swim-fin employing a buoyant material to overcome the negative buoyancy of the legs and feet of a swimmer. A hollow foot pocket 14 having a convex curvature extends from a sole portion 12 and is provided with an orifice 15 at the forward end.
Gwynne is directed to a swim fin in U.S. Pat. No. 3,239,857 that comprises a shoe 10 having a flat platform piece 11 and a vamp forming a socket 12 for containing the forepart of the swimmer's foot. Also, a fin blade 16, a heel portion 13, and a leg-encasing member 20 that engages the lower part of the swimmer's leg. There is, however, an opening between the heel portion 13 and the leg-encasing member 20.
U.S. Pat. No. 3,422,470 of Mares teaches a swimming-fin comprising a shoe section 1 and a webb 2 extending forwardly from the toe end of shoe section 1. As illustrated in FIGS. 1 and 2, shoe section 1 is closed at the toe but it is not disclosed in the text whether there is sufficient room in the front part of shoe section 1 for the swimmer to flex his foot.
Rasmussen, in U.S. Pat. No. 4,007,506, is directed to a swim-fin having a foot portion 12 and a blade portion 14. The foot portion 12 includes two side walls 16 and 17, a heel 18, a sole 19, and an upper wall 20 which together define an opening 22 into which the swimmer inserts his foot. There is no disclosure in this prior art of how much room there is inside the foot portion to flex the swimmer's foot.
U.S. Pat. No. 4,541,810, issue to Wenzel, employs a swimming flipper that is adapted to receive both feet, ankles, and to some extent, the lower part of the swimmer's legs. The specification makes clear that the feet 13 of the swimmer or user are meant to be received "snugly" within foot-receiving pocket 14.
Garofalo discloses in U.S. Pat. No. 4,738,645 a swim fin which directs the fluid flow produced during swimming in the active propulsion direction. Referring to FIGS. 8, 11 and 12, the fin comprises a shoe portion 101, a blade portion 201, and two side ribs 301 for stiffening the blade 201. The fin has an enlarged bulbous area at the front end of the shoe portion 101. However, the shoe portion 101 is not enclosed.
U.S. Pat. No. 4,752,259 issued to Tackett et al is directed to swin fins generally. Referring to FIG. 2, the swim fin 10 comprises a rubber shoe section section 12, a fin portion 14 having an outer section 16 and an inner section 18, rotating hinges 20 to connect the outer section 16 and the inner section 18, and a catch 22 to lock the hinges 20 for the purpose of keeping the outer and inner portions either in extended or folded positions relative to each other. As shown in FIG. 2, the forward area of shoe section 12 is somewhat bulbous, in configuration.
Of considerable relevance is U.S. Pat. No. 4,857,024 issued in Aug. 15, 1989 to the inventor. While this patent is for a single fin, with an open toe section, much of the same action of the fin is incorporated into this invention in combination. Other elements are different enough as to make the combination distinguish over the inventors own prior art.
It will be noted that while all of the above prior art cited has some method of foot retension, none disclose a bulbous shoe portion that would allow the foot of the swimmer to flex within the shoe and certainly not the combination of the flex action with the flexing movement of the fin itself creating a flipping or snapping action to propel the swimmer.